Enter two side lengths and leave one blank.
Geometry Calculator
Pythagorean Theorem Calculator
Find the missing side of a right triangle from the other two sides and check whether the hypotenuse is valid.
Instant answer
Formula breakdown
Browser-based
Mobile friendly
Interactive calculator
Enter your values
Use the example values or replace them with your own. Required validation happens before the calculation.
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Calculated answer
Result
Simple workflow
How to use the Pythagorean Theorem Calculator
Follow these steps to get a reliable result and understand how it was produced.
Square the known sides and rearrange a²+b²=c².
Take the positive square root for the missing length.
Understanding the calculation
The hypotenuse c is opposite the right angle and must be the longest side. Leave exactly one side blank.
a²+b²=c²The result panel substitutes your numbers into this relationship and shows the important intermediate values.
Common uses
- Construction diagonals
- Right-triangle homework
- Distance on coordinate grids
Accuracy tips
- The theorem applies only to right triangles.
- The hypotenuse must be the longest side.
- Side lengths must be positive.
Helpful answers
Pythagorean Theorem Calculator FAQs
Important details about formulas, inputs, limitations, and result interpretation.
Which side is c?
c is the hypotenuse, opposite the 90-degree angle.
Can I solve for a leg?
Yes. Enter the other leg and hypotenuse, leaving the desired leg blank.
Why can the square-root expression become negative?
That happens when the entered hypotenuse is not longer than the known leg.
Does this determine whether any triangle is right-angled?
You can compare whether the largest side squared equals the sum of the other two squares.